michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: /*
michael@0:  * This file defines a wrapper around libudev so we can avoid
michael@0:  * linking directly to it and use dlopen instead.
michael@0:  */
michael@0: 
michael@0: #ifndef HAL_LINUX_UDEV_H_
michael@0: #define HAL_LINUX_UDEV_H_
michael@0: 
michael@0: #include <dlfcn.h>
michael@0: 
michael@0: #include "mozilla/ArrayUtils.h"
michael@0: 
michael@0: namespace mozilla {
michael@0: 
michael@0: struct udev;
michael@0: struct udev_device;
michael@0: struct udev_enumerate;
michael@0: struct udev_list_entry;
michael@0: struct udev_monitor;
michael@0: 
michael@0: class udev_lib {
michael@0:  public:
michael@0:   udev_lib() : lib(nullptr),
michael@0:                udev(nullptr) {
michael@0:     // Be careful about ABI compat! 0 -> 1 didn't change any
michael@0:     // symbols this code relies on, per:
michael@0:     // https://lists.fedoraproject.org/pipermail/devel/2012-June/168227.html
michael@0:     const char* lib_names[] = {"libudev.so.0", "libudev.so.1"};
michael@0:     // Check whether a library is already loaded so we don't load two
michael@0:     // conflicting libs.
michael@0:     for (unsigned i = 0; i < ArrayLength(lib_names); i++) {
michael@0:       lib = dlopen(lib_names[i], RTLD_NOLOAD | RTLD_LAZY | RTLD_GLOBAL);
michael@0:       if (lib) {
michael@0:         break;
michael@0:       }
michael@0:     }
michael@0:     // If nothing loads the first time through, it means no version of libudev
michael@0:     // was already loaded.
michael@0:     if (!lib) {
michael@0:       for (unsigned i = 0; i < ArrayLength(lib_names); i++) {
michael@0:         lib = dlopen(lib_names[i], RTLD_LAZY | RTLD_GLOBAL);
michael@0:         if (lib) {
michael@0:           break;
michael@0:         }
michael@0:       }
michael@0:     }
michael@0:     if (lib && LoadSymbols()) {
michael@0:       udev = udev_new();
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   ~udev_lib() {
michael@0:     if (udev) {
michael@0:       udev_unref(udev);
michael@0:     }
michael@0: 
michael@0:     if (lib) {
michael@0:       dlclose(lib);
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   operator bool() {
michael@0:     return udev;
michael@0:   }
michael@0: 
michael@0:  private:
michael@0:   bool LoadSymbols() {
michael@0: #define DLSYM(s) \
michael@0:   do { \
michael@0:     s = (typeof(s))dlsym(lib, #s); \
michael@0:     if (!s) return false; \
michael@0:   } while (0)
michael@0: 
michael@0:     DLSYM(udev_new);
michael@0:     DLSYM(udev_unref);
michael@0:     DLSYM(udev_device_unref);
michael@0:     DLSYM(udev_device_new_from_syspath);
michael@0:     DLSYM(udev_device_get_devnode);
michael@0:     DLSYM(udev_device_get_parent_with_subsystem_devtype);
michael@0:     DLSYM(udev_device_get_property_value);
michael@0:     DLSYM(udev_device_get_action);
michael@0:     DLSYM(udev_device_get_sysattr_value);
michael@0:     DLSYM(udev_enumerate_new);
michael@0:     DLSYM(udev_enumerate_unref);
michael@0:     DLSYM(udev_enumerate_add_match_subsystem);
michael@0:     DLSYM(udev_enumerate_scan_devices);
michael@0:     DLSYM(udev_enumerate_get_list_entry);
michael@0:     DLSYM(udev_list_entry_get_next);
michael@0:     DLSYM(udev_list_entry_get_name);
michael@0:     DLSYM(udev_monitor_new_from_netlink);
michael@0:     DLSYM(udev_monitor_filter_add_match_subsystem_devtype);
michael@0:     DLSYM(udev_monitor_enable_receiving);
michael@0:     DLSYM(udev_monitor_get_fd);
michael@0:     DLSYM(udev_monitor_receive_device);
michael@0:     DLSYM(udev_monitor_unref);
michael@0: #undef DLSYM
michael@0:     return true;
michael@0:   }
michael@0: 
michael@0:   void* lib;
michael@0: 
michael@0:  public:
michael@0:   struct udev* udev;
michael@0: 
michael@0:   // Function pointers returned from dlsym.
michael@0:   struct udev* (*udev_new)(void);
michael@0:   void (*udev_unref)(struct udev*);
michael@0: 
michael@0:   void (*udev_device_unref)(struct udev_device*);
michael@0:   struct udev_device* (*udev_device_new_from_syspath)(struct udev*,
michael@0:                                                       const char*);
michael@0:   const char* (*udev_device_get_devnode)(struct udev_device*);
michael@0:   struct udev_device* (*udev_device_get_parent_with_subsystem_devtype)
michael@0:     (struct udev_device*, const char*, const char*);
michael@0:   const char* (*udev_device_get_property_value)(struct udev_device*,
michael@0:                                                 const char*);
michael@0:   const char* (*udev_device_get_action)(struct udev_device*);
michael@0:   const char* (*udev_device_get_sysattr_value)(struct udev_device*,
michael@0:                                                const char*);
michael@0: 
michael@0:   struct udev_enumerate* (*udev_enumerate_new)(struct udev*);
michael@0:   void (*udev_enumerate_unref)(struct udev_enumerate*);
michael@0:   int (*udev_enumerate_add_match_subsystem)(struct udev_enumerate*,
michael@0:                                             const char*);
michael@0:   int (*udev_enumerate_scan_devices)(struct udev_enumerate*);
michael@0:   struct udev_list_entry* (*udev_enumerate_get_list_entry)
michael@0:     (struct udev_enumerate*);
michael@0: 
michael@0:   struct udev_list_entry* (*udev_list_entry_get_next)(struct udev_list_entry *);
michael@0:   const char* (*udev_list_entry_get_name)(struct udev_list_entry*);
michael@0: 
michael@0:   struct udev_monitor* (*udev_monitor_new_from_netlink)(struct udev*,
michael@0:                                                         const char*);
michael@0:   int (*udev_monitor_filter_add_match_subsystem_devtype)
michael@0:     (struct udev_monitor*, const char*, const char*);
michael@0:   int (*udev_monitor_enable_receiving)(struct udev_monitor*);
michael@0:   int (*udev_monitor_get_fd)(struct udev_monitor*);
michael@0:   struct udev_device* (*udev_monitor_receive_device)(struct udev_monitor*);
michael@0:   void (*udev_monitor_unref)(struct udev_monitor*);
michael@0: };
michael@0: 
michael@0: } // namespace mozilla
michael@0: 
michael@0: #endif // HAL_LINUX_UDEV_H_